# How do you evaluate csc 180 ?

Since $\csc \left(x\right) = \frac{1}{\sin} \left(x\right)$, you have
$\csc \left(180\right) = \frac{1}{\sin} \left(180\right)$
But since $\sin \left(180\right) = 0$, you can't divide by it, and thus $\csc \left(180\right)$ is not defined.